// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2012 ARM Ltd.
 * Copyright (c) 2014 The Linux Foundation
 */
#include <linux/dma-direct.h>
#include <linux/dma-noncoherent.h>
#include <linux/dma-contiguous.h>
#include <linux/init.h>
#include <linux/genalloc.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

static struct vm_struct *__dma_common_pages_remap(struct page **pages,
                        size_t size, unsigned long vm_flags, pgprot_t prot,
                        const void *caller)
{
        struct vm_struct *area;

        area = get_vm_area_caller(size, vm_flags, caller);
        if (!area)
                return NULL;

        if (map_vm_area(area, prot, pages)) {
                vunmap(area->addr);
                return NULL;
        }

        return area;
}

/*
 * Remaps an array of PAGE_SIZE pages into another vm_area.
 * Cannot be used in non-sleeping contexts
 */
void *dma_common_pages_remap(struct page **pages, size_t size,
                        unsigned long vm_flags, pgprot_t prot,
                        const void *caller)
{
        struct vm_struct *area;

        area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
        if (!area)
                return NULL;

        area->pages = pages;

        return area->addr;
}

/*
 * Remaps an allocated contiguous region into another vm_area.
 * Cannot be used in non-sleeping contexts
 */
void *dma_common_contiguous_remap(struct page *page, size_t size,
                        unsigned long vm_flags,
                        pgprot_t prot, const void *caller)
{
        int i;
        struct page **pages;
        struct vm_struct *area;

        pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
        if (!pages)
                return NULL;

        for (i = 0; i < (size >> PAGE_SHIFT); i++)
                pages[i] = nth_page(page, i);

        area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);

        kfree(pages);

        if (!area)
                return NULL;
        return area->addr;
}

/*
 * Unmaps a range previously mapped by dma_common_*_remap
 */
void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
{
        struct vm_struct *area = find_vm_area(cpu_addr);

        if (!area || (area->flags & vm_flags) != vm_flags) {
                WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
                return;
        }

        unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
        vunmap(cpu_addr);
}

#ifdef CONFIG_DMA_DIRECT_REMAP
static struct gen_pool *atomic_pool __ro_after_init;

#define DEFAULT_DMA_COHERENT_POOL_SIZE  SZ_256K
static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE;

static int __init early_coherent_pool(char *p)
{
        atomic_pool_size = memparse(p, &p);
        return 0;
}
early_param("coherent_pool", early_coherent_pool);

int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
{
        unsigned int pool_size_order = get_order(atomic_pool_size);
        unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
        struct page *page;
        void *addr;
        int ret;

        if (dev_get_cma_area(NULL))
                page = dma_alloc_from_contiguous(NULL, nr_pages,
                                                 pool_size_order, false);
        else
                page = alloc_pages(gfp, pool_size_order);
        if (!page)
                goto out;

        arch_dma_prep_coherent(page, atomic_pool_size);

        atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
        if (!atomic_pool)
                goto free_page;

        addr = dma_common_contiguous_remap(page, atomic_pool_size, VM_USERMAP,
                                           prot, __builtin_return_address(0));
        if (!addr)
                goto destroy_genpool;

        ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr,
                                page_to_phys(page), atomic_pool_size, -1);
        if (ret)
                goto remove_mapping;
        gen_pool_set_algo(atomic_pool, gen_pool_first_fit_order_align, NULL);

        pr_info("DMA: preallocated %zu KiB pool for atomic allocations\n",
                atomic_pool_size / 1024);
        return 0;

remove_mapping:
        dma_common_free_remap(addr, atomic_pool_size, VM_USERMAP);
destroy_genpool:
        gen_pool_destroy(atomic_pool);
        atomic_pool = NULL;
free_page:
        if (!dma_release_from_contiguous(NULL, page, nr_pages))
                __free_pages(page, pool_size_order);
out:
        pr_err("DMA: failed to allocate %zu KiB pool for atomic coherent allocation\n",
                atomic_pool_size / 1024);
        return -ENOMEM;
}

bool dma_in_atomic_pool(void *start, size_t size)
{
        return addr_in_gen_pool(atomic_pool, (unsigned long)start, size);
}

void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
{
        unsigned long val;
        void *ptr = NULL;

        if (!atomic_pool) {
                WARN(1, "coherent pool not initialised!\n");
                return NULL;
        }

        val = gen_pool_alloc(atomic_pool, size);
        if (val) {
                phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);

                *ret_page = pfn_to_page(__phys_to_pfn(phys));
                ptr = (void *)val;
                memset(ptr, 0, size);
        }

        return ptr;
}

bool dma_free_from_pool(void *start, size_t size)
{
        if (!dma_in_atomic_pool(start, size))
                return false;
        gen_pool_free(atomic_pool, (unsigned long)start, size);
        return true;
}

void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
                gfp_t flags, unsigned long attrs)
{
        struct page *page = NULL;
        void *ret;

        size = PAGE_ALIGN(size);

        if (!gfpflags_allow_blocking(flags) &&
            !(attrs & DMA_ATTR_NO_KERNEL_MAPPING)) {
                ret = dma_alloc_from_pool(size, &page, flags);
                if (!ret)
                        return NULL;
                goto done;
        }

        page = __dma_direct_alloc_pages(dev, size, dma_handle, flags, attrs);
        if (!page)
                return NULL;

        /* remove any dirty cache lines on the kernel alias */
        arch_dma_prep_coherent(page, size);

        if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
                ret = page; /* opaque cookie */
                goto done;
        }

        /* create a coherent mapping */
        ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
                        arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
                        __builtin_return_address(0));
        if (!ret) {
                __dma_direct_free_pages(dev, size, page);
                return ret;
        }

        memset(ret, 0, size);
done:
        *dma_handle = phys_to_dma(dev, page_to_phys(page));
        return ret;
}

void arch_dma_free(struct device *dev, size_t size, void *vaddr,
                dma_addr_t dma_handle, unsigned long attrs)
{
        if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
                /* vaddr is a struct page cookie, not a kernel address */
                __dma_direct_free_pages(dev, size, vaddr);
        } else if (!dma_free_from_pool(vaddr, PAGE_ALIGN(size))) {
                phys_addr_t phys = dma_to_phys(dev, dma_handle);
                struct page *page = pfn_to_page(__phys_to_pfn(phys));

                vunmap(vaddr);
                __dma_direct_free_pages(dev, size, page);
        }
}

long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
                dma_addr_t dma_addr)
{
        return __phys_to_pfn(dma_to_phys(dev, dma_addr));
}
#endif /* CONFIG_DMA_DIRECT_REMAP */